Electron transfer coupling with biogenic elements conversion in farmland soil: A review

Farmland soil is a complex system involving the conversion of multiple biogenic elements, which plays a key role in maintaining soil ecological balance. Extracellular electron transfer (EET) is an essential driving force for material circulation and energy exchange. Thus, it affects the biogeochemical processes and cycles of soil elements, including mineral formation and evolution, nutrient cycling and even the removal of pollutants and the improvement of cultivated land quality. This review summarizes the progress of research on electron transfer in farmland soil. It provides an overview of electroactive microorganisms, electron transfer modes, and their coupled conversion with carbon, nitrogen, sulfur, and iron elements. Afterwards, future research directions are expected, including an in-depth exploration of electron transfer mechanisms, optimization of electron transfer pathways, and improvement of biogenic element conversion. This review puts forward a new way to regulate the biotransformation of elements and provides support for improving the fertility of farmland soil and promoting the sustainable development of agriculture. • Classification and distribution environments of EMs were overviewed. • Electron transfer modes were categorized in terms of the pathways and distances. • Microbial EET drives multi-element biogeochemical cycles in farmland soil. • Research on the EET mechanism would boost applications of soil bioelectronics.